1. Field of the Invention
The present invention relates to a cooled flameholder for a turbojet-engine. More specifically, the invention relates to a cooled, carbureted flameholder for a turbojet-engine.
2. Description of the Related Art
French patent 2,709,342 discloses an afterburner for a bypass turbojet-engine. The bypass turbojet-engine comprises an outer, substantially annular duct and an exhaust duct contained inside the outer duct. The exhaust duct comprises an annular outer wall and an annular inner wall each having the same longitudinal axis as the outer duct. The exhaust duct and the outer duct define a first flow passage for bypass air. The annular outer wall and the annular inner wall define a second passage therebetween for the combustion gases. The afterburner further comprises an annular afterburner wall which has the same longitudinal axis as the outer duct and is mounted inside the outer duct from which it is spaced by a given distance to define a cooling-air passage. The afterburner wall also defines an afterburner chamber downstream of the first and second passages. The afterburner further comprises flameholders running in radial planes relative to the axis at least inside the second passage. Each flameholder has the shape of a dihedral formed by two outer plates intersecting at a common ridge and has an outer V-section with the tip pointed upstream relative to the overall axial direction of flow of the combustion gases. Each flameholder moreover includes a multi-perforated ventilation tube, to cool the outer plates by cooling air tapped from the first passage, and at least one radial fuel conduit fitted with fuel injection orifices.
The ventilation tube has a circular cross section, is mounted near the ridge of the dihedral, and includes orifices to cool the outer plates of the dihedral. A cross-sectionally semi-circular heat shield is mounted downstream of the fuel conduit between the downstream edges of the dihedral plates and is fitted with lateral, axial slots to allow the air/fuel mixture to flow into the afterburner chamber. The injection orifices of the fuel conduit consist of holes which are in substantially radial planes and point toward the inner walls of the dihedral plates. This flameholder is said to be "carbureted".
French patent 2,696,502 discloses radial flameholders which are also in the shape of dihedrals and include ventilation tubes to cool each dihedral. However, this flameholder is both without a fuel conduit and without a heat shield. In this design, the fuel is injected upstream of the flameholder through fuel conduits mounted laterally on the connecting arms configured in an alternating manner between the flameholders. The injected fuel drains along the outer flameholder walls. The cross-section of the ventilation tube is larger than that of the cylindrical tube of the French patent 2,709,342, thereby assuring improved cooling of the dihedral walls; however, the fuel conduits are exposed to the heat of the combustion gases, risking coking and vapor-lock malfunctions.